The present invention relates to a dispenser for the dispensing of paste compositions, having a piston which is movable in the emptying direction within a dispenser housing; a stopper part which serves to close off the piston and is driven in sealing manner into the piston; a stopper seat disposed within the piston and the dispenser housing is adapted for venting by means of a vent zone located in the region of the stopper seat.
Ventable dispenser vessels are already known from various embodiments. Federal Republic of Germany Utility Model GM No. 18 21 202 discloses, for instance, a dispenser vessel whose closure has a stopper part which is formed in part with arms which leave vent grooves free between a stopper seat and the stopper part. In a second region in this known dispenser vessel the stopper part is formed with a continuous cylindrical wall. The stopper part can, first of all, be driven into the stopper seat in a first position having vent paths open and the vessel can them be completely closed, by the further inward driving of the stopper part, the cylindrical wall of the stopper part coming against the stopper seat.
Federal Republic of Germany Utility Model GM No. 60 25 352 also discloses a dispenser in which the vent zone is formed by a roughened region of the inner surface of the dispenser housing opened on the bottom. A piston which is inserted into the dispenser housing naturally does not lie in completely sealing fashion against the wall surface of the dispenser housing in the region of the roughened zone, so that the emergence of air is possible.
In the last-mentioned dispenser, the function of intended non-tightness depends greatly on the viscosity and nature of the material to be introduced. The desired evacuation of the enclosed air is not obtained in all cases. For instance, fatty filling substances very easily clog the roughened annular slot. As a result of the vibrations which cannot be completely excluded in automatic filling machines and the stepwise transport from station to station, the surface of the filling can tilt so that the zone of roughening is already wetted in advance.
The first-mentioned dispenser does not have these disadvantages. However, also in the case of this known dispenser, the sealing obtained is not entirely satisfactory. Thus grooves or arms are made in a manner which is expensive to manufacture in the wall of the stopper part in order to obtain the desired vent channels. Furthermore, a relatively small stopper part must be driven into the stopper seat, which either makes an expensive device necessary or else must be effected by hand.
In this connection there is also known as prior art Federal Republic of Germany No. 10 34 554 which has a dispenser closure with stopper part connected via tear-off arms. A connection to the inside of the dispenser vessel, when the stopper part is not completely driven in, is, however, only present in this known dispenser closure by means--also in a relatively expensive manner--of a central bore as well as a radial bore in the stopper part.